Electronic brake device

This application claims the benefit of priority to Korean Patent Application No. 10-2021-0090423, filed on Jul. 9, 2021, the disclosure of which is incorporated herein by reference in its entirety.

The present disclosure relates to an electronic hydraulic brake device and, more particularly, an electronic hydraulic brake device that can perform redundancy braking.

Description of this section only provides the background information of embodiments without configuring the related art.

In general, an electronic hydraulic brake system adjusts the braking pressure of each wheel using a hydraulic modulator after pedal pressure by a driver is sensed through a sensor.

An electronic hydraulic brake system includes a sensor that senses the stroke distance of a pedal to be able to know the braking pressure that a driver wants, and a pedal simulator that enables a driver to feel pedal pressure such as in a common hydraulic brake system.

A control unit determines braking force required by a driver through a pedal stroke sensor, a pressure sensor, etc., and generates braking force at a wheel brake by driving a specific wheel brake unit.

A wheel brake unit usually includes a main master cylinder structure for generating hydraulic pressure, and a hydraulic circuit and valves for transmitting hydraulic pressure generated by the main master to brake devices mounted on wheels of a vehicle.

is a block diagram showing an example of an electronic hydraulic brake system of the related art.

The electronic hydraulic brake system of the related art shown inis configured to perform not only a fundamental function for providing a reaction feeling to a driver while sensing the degree of pedal effort by the driver by means of a pedal simulator, but a function of a backup master cylinder for providing redundancy braking force when a main braking device malfunctions.

That is, a hydraulic circuit and valves are disposed so that a brake can be driven by pedal effort from a driver even though a main master cylinder that is driven by a motor does not work in a fallback mode that is the situation in which power is not supplied to a brake system or there is a problem with the function of an electric actuator, an electronic control valve, etc.

However, an electronic hydraulic brake system of the related art is configured to provide physical braking force by a person under the assumption that a drive basically keeps paying attention to surrounding objects while driving even in the fallback mode. That is, according to an electronic hydraulic brake system of the related art, for example, when a vehicle is driven in a smart cruise control mode or an autonomous mode, a driver does not quickly take measures against malfunction of the braking device and misses the timing for physically operating a pedal, which may result in a large accident.

Further, since an electronic hydraulic brake system of the related art is not equipped with a pressure-increasing means such as a pressure booster on a backup master cylinder, there is a difficulty in that even if a driver depresses a brake pedal at appropriate timing, braking pressure and inclination of an increase thereof are not generated to be suitable for emergency braking.

According to at least one aspect, the present disclosure provides an electronic brake comprising: a plurality of wheel brake units supplying braking force to wheels of a vehicle; a main braking device configured to generate pressure of brake oil in cooperation with a main braking motor; a secondary braking device configured to generate pressure of brake oil in cooperation with a secondary braking motor; a hydraulic circuit valve device configured to selectively transmit the pressure of brake oil generated by the main braking device or the secondary braking device to the plurality of wheel brake units; a main controller configured to control the main braking motor of the main braking device in accordance with braking input; and an assistant controller configured to control the secondary braking motor of the secondary braking device in accordance with braking input and to control the hydraulic circuit valve device to transmit the pressure of brake oil generated by the secondary braking device to only some wheel brake units of the plurality of wheel brake units when the main controller or the main braking device malfunctions.

Accordingly, the present disclosure provides an electronic hydraulic brake system that can appropriately provide redundancy braking force, that is, an electronic hydraulic brake system that provides a so-called redundancy function, in the situation in which a driver does not drive or gives less attention to driving such as autonomous driving or smart cruise control and a main braking device malfunctions.

Further, the present disclosure provides an electronic hydraulic brake system that has a more space-efficient small size and can perform a required redundancy function.

The objectives of the present disclosure are not limited to the objects described above and other objects will be clearly understood by those skilled in the art from the following description.

Hereinafter, some exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, like reference numerals preferably designate like elements, although the elements are shown in different drawings. Further, in the following description of some embodiments, a detailed description of known functions and configurations incorporated therein will be omitted for the purpose of clarity and for brevity.

Additionally, various terms such as first, second, A, B, (a), (b), etc., are used solely to differentiate one component from the other but not to imply or suggest the substances, order, or sequence of the components. Throughout this specification, when a part ‘includes’ or ‘comprises’ a component, the part is meant to further include other components, not to exclude thereof unless specifically stated to the contrary. The terms such as ‘unit,’ ‘module,’ and the like refer to one or more units for processing at least one function or operation, which may be implemented by hardware, software, or a combination thereof.

is a block diagram schematically showing the structure of an electronic hydraulic brake system according to an embodiment of the present disclosure.

is a hydraulic circuit diagram schematically showing the structure of the electronic hydraulic brake system according to an embodiment of the present disclosure.

Referring to, an electronic hydraulic brake systemaccording to an embodiment of the present disclosure includes a plurality of wheel brake units w, w, w, and wsupplying braking force to wheel of a vehicle, a main braking deviceconfigured to change the pressure of brake oil in cooperation with a main braking motor, a secondary braking deviceconfigured to change the pressure of brake oil in cooperation with a secondary braking motor, a hydraulic circuit valve deviceconfigured to selectively transmit the hydraulic pressure of brake oil to the plurality of wheel brake units w, w, w, and w, a main controllerconfigured to control the main braking motor of the main braking device in accordance with braking input PSS, and an assistant controllerconfigured to control the secondary braking motor of the secondary braking devicein accordance with braking input PSS.

A reservoir is installed to supplement insufficient liquid when the volume of the liquid is not sufficient in accordance with variation of temperature in a system using liquid, and is also called a reservoir tank.

Brake oil is stored in the reservoirused in the electronic hydraulic brake system.

A pedal that is rotated by operation of a user is connected to a pedal simulator.

The pedal simulatoris configured to provide corresponding reaction force to the pedal with movement of the pedal. Such reaction force may be defined as resistance or pedal effort by a driver when a brake pedal is depressed. In the present disclosure, the pedal simulatordoes not fluid-communicate with a hydraulic circuit valve deviceof the brake system. That is, the pedal simulatoris separated from the hydraulic circuit valve device in terms of fluid. Further, the pedal simulatoris separated from the reservoiras well in terms of fluid. That is, the pedal simulatormay be physically integrated with the main braking deviceand the secondary braking devicein the present disclosure, but the present disclosure is not limited to this embodiment and includes the case in which the pedal simulatoris provided separately from the main braking deviceand the secondary braking deviceto be able to transmit a braking signal.

The pedal simulatoraccording to the present disclosure is not limited to the structure according to the embodiment shown in. The structure and function of the pedal simulatormay be configured in various types within the spirit that changes pedal effort and the pressure of brake oil therein.

Further, in the electronic hydraulic brake system according to the present disclosure, the pedal simulatormay be omitted. That is, a braking signal may correspond to a braking signal or a deceleration signal that is provided by an autonomous system and a driver may be excluded from driving actions including braking. In this case, the electronic hydraulic brake system according to the present disclosure may be a system, that is, a so-called Braking by Wire (BBW) system in which braking input PSS that is input to the main controllerand the assistant controlleris a signal generated by an autonomous controller for driving.

The hydraulic circuit valve devicefluid-communicates with the main braking device, the secondary braking device, and the plurality of wheel brake units w, w, w, and wand is configured to be able to change a channel inside, that is, a channel in which hydraulic pressure is applied or a channel through which oil flows between the reservoir, the main braking device, the secondary braking device, and the plurality of wheel brake units w, w, w, and win response to a first valve control signal VCS, VCSand a second valve control signal VCS, VCS.

The plurality of wheel brake units w, w, w, and wis configured to apply braking force to the wheels of a vehicle using hydraulic pressure. The plurality of wheel brake units w, w, w, and w, for example, may be caliper brakes. The plurality of wheel brake units w, w, w, and wmay selectively fluid-communicate with one or more of the reservoir, the main braking device, and the secondary braking devicethrough the hydraulic circuit valve device. For example, hydraulic pressure generated at the main braking deviceor the secondary braking devicemay be applied to the plurality of wheel brake units w, w, w, and wthrough the hydraulic circuit valve device. In this case, the plurality of wheel brake units w, w, w, and wcan apply braking force corresponding to hydraulic pressure to the wheels of a vehicle. The plurality of wheel brake units w, w, w, and wmay fluid-communicate with the reservoirthrough the hydraulic circuit valve device. In this case, the hydraulic pressure of the plurality of wheel brake units w, w, w, and wmay be atmospheric pressure or a pressure corresponding to the atmospheric pressure, and the braking force may be removed.

The main braking deviceis configured to change the pressure of brake oil inside in correspondence to a first motor control signal MCS. The main braking devicehas a hollow structure. The main braking deviceincludes a piston disposed in the internal space thereof and two hydraulic chambers separated by the piston. The piston is configured to reciprocate to a side, that is, between the hydraulic chambers with rotation of a motor.

When the main braking motor is rotated clockwise or counterclockwise by the first motor control signal MCS, the piston moves to a side or another side and can separately press the brake oil in the two hydraulic chambers.

The main braking devicemay selectively fluid-communicate with one or more of the reservoir, the secondary braking device, and the plurality of wheel brake units w, w, w, and wthrough the hydraulic circuit valve device.

The secondary braking deviceis configured to change the pressure of brake oil inside in correspondence to a second motor control signal MCS. The secondary braking devicemay be an oil pump structure, and for example, may be configured to pump brake oil with rotation of the secondary braking motor when the secondary braking motor is operated by a second motor control signal MCS. An oil flow path passing through the secondary braking devicecan be transmitted to the plurality of wheel brake units w, w, w, and wthrough the hydraulic circuit valve device. In detail, the hydraulic pressure generated at the secondary braking devicecan be transmitted to channels of wheels sequentially through a second main braking valveand a second traction control valve. Further, referring to, the secondary braking deviceaccording to an embodiment of the present disclosure is disposed between a chamber formed ahead of the piston of the main braking deviceand the reservoir.

However, in an embodiment of the present disclosure, the secondary braking devicemay be a pump having a small capacity or a pump having small output in comparison to the main braking device. Accordingly, the secondary braking devicemay be configured to supply hydraulic pressure only to one, two, or three wheel brake units of four wheel brake units. In the embodiment of the present disclosure shown in the figures, the secondary braking deviceis configured to transmit hydraulic pressure to only two wheel brake units wand wthrough the hydraulic circuit valve device.

The hydraulic circuit valve devicefluid-communicates with one or more of the reservoir, the main braking device, and the secondary braking device, and the plurality of wheel brake units w, w, w, and w.

The hydraulic circuit valve deviceis configured to be able to change an oil flow path inside, that is, an oil flow path through which oil is transmitted between the reservoir, the main braking device, and the secondary braking device, and the plurality of wheel brake units w, w, w, and w, in response to the first valve control signal VCSof the main controllerand the second valve control signal VCSof the assistant controller.

In an embodiment of the present disclosure, the hydraulic circuit valve deviceincludes some or all of a plurality of main braking control valvesrelated to the operation of the main braking device, a plurality of secondary braking control valvesrelated to the operation of the secondary braking device, and a plurality of posture control valvesrelated to posture control of a vehicle.

The plurality of main braking control valvesmay include a first main braking control valvethat opens/closes a hydraulic pressure path between the reservoirand the main braking deviceand a hydraulic pressure path between the reservoirand the posture control valves, and a second main braking control valvethat opens/closes a hydraulic pressure path between the secondary braking deviceand the main braking deviceand a hydraulic pressure path between the secondary braking deviceand the posture control valves.

The second main braking valveis disposed between a forward chamber of the main braking deviceand the reservoir. The second main braking valveis configured such that whether to transmit hydraulic pressure to the wheel brake units from the secondary braking device is determined in accordance with opening/closing of the second main braking valve. When a wheel brake is pressed, the second main braking valveis closed, thereby preventing working fluid in the forward chamber from being transmitted to the reservoir.

The plurality of secondary braking control valvesmay include a first assistant braking valveand a second assistant braking valvethat open/close a hydraulic pressure path between the reservoirand the second main braking valve.

The first assistant braking valveand the second assistant braking valveare disposed in parallel between the second main braking valveand the reservoir. The first assistant braking valveand the second assistant braking valveare configured to adjust the hydraulic pressure at the wheel brake units.

The first assistant braking valveis open during normal times and is used to control a set pressure at wheels connected with some wheel brakes wand w. In detail, when braking pressure is transmitted to some wheel brakes wand w, the amount of fluid required to generate the intended braking pressure is sent to the wheels and the other amount of fluid is sent to the reservoir. Accordingly, it is possible to generate braking pressure as intended at the wheel brakes wand w.

The second assistant braking valveis open or closed during normal times, depending on whether a current is applied, and is configured to be opened when there is a problem with the main braking unit, as in, and when the pressure of a wheel to which the secondary braking devicetransmits hydraulic pressure is decreased.

When pressure at the wheel brake units is decreased, the second main braking valveis opened, so working fluid is transmitted from the forward chamber of the main braking deviceto the second main braking valve. Since the second main braking valveis open, working fluid is transmitted to the first assistant braking valveand/or the second assistant braking valvefrom the second main braking valve. When the pressure of the wheel brakes is decreased, working fluid is transmitted to the reservoir because that first assistant braking valveand/or the second assistant braking valveis open. That is, working fluid is sequentially transmitted to the forward chamber, the second main braking valve, the first and second assistant braking valvesand, and the reservoir.

The plurality of posture control valvesis configured to adjust hydraulic pressure that is applied to the plurality of wheel brake units w, w, w, and won the basis of a posture control signal of the controller. The posture control valvesare configured to open/close the oil flow path between the main braking deviceand the plurality of wheel brake units w, w, w, and wor the oil flow path between the secondary braking deviceand the plurality of wheel brake units w, w, w, and won the basis of a posture control signal.

The posture control valvesare configured to independently control the braking force of each of the plurality of wheel brake units w, w, w, and wand are configured to implement the functions of an Anti-lock Braking System (ABS), a Traction Control system (TCS), and Electronic Stability Control (ECS).

The posture control valvesinclude four pairs of inlet valves and outlet valves provided such that one inlet valve and one outlet valve are disposed in each brake channel for directly supplying oil to each of the wheel brake units w, w, w, and wor discharging oil. Further, the posture control valvesinclude a first traction control valve, a second traction control valve, and a mixing valvefor distributing hydraulic pressure generated from the main braking deviceor the secondary braking deviceto each brake channel.

Further, when the main braking deviceor the main controllermalfunctions, the secondary braking motor of the secondary braking deviceis operated in accordance with the second motor control signal MCSof the assistant controller. The secondary braking deviceoperation in cooperation with the secondary braking motor transmits pressed brake oil to the hydraulic circuit valve device. The brake oil is transmitted to the plurality of wheel brake units w, w, w, and w, so effective redundancy braking by electronic control can be achieved in a redundancy braking situation.

That is, according to the present disclosure, it is possible to appropriately provide redundancy braking force even if a main braking device malfunctions in the situation in which a driver does not drive or gives less attention to driving such as smart cruise control or autonomous driving.

Further, the present disclosure further includes an additional device having a similar function in consideration of the possibility of malfunction in devices that perform an electronic control type brake function, so it is possible to implement a brake system that can prevent the possibility of problems due to such malfunction and secures so-called redundancy. In particular, according to the present disclosure, it is possible to achieve an appropriate braking function in a situation with malfunction of a main braking device by only adding a pump and a valve system without actually employing a separate additional brake system in terms of securing such redundancy.